Processors and other highly integrated electronic components require accurate voltage supplies capable of supplying large amounts of current and power while maintaining tight voltage regulation and subject to tight implementation area constraints. With increasing complexity of such electronic systems, industry trends are toward digital power management and digital command interfaces such as PMBus (Power Management Bus), AVS (Adaptive Voltage Scaling), SVID (Serial Voltage Identification), SVI/SVI2 (Switched Virtual Interface), etc. These command interfaces can be implemented in various ways, but point-to-point interfaces are highly desirable for high speed and simplicity, which has led to several multi-rail over single bus approaches where ‘multi-rail’ refers to multiple voltage rails each regulated at a defined voltage level.
However, the nature of point-to-point interfaces is such that the voltage rail definition must explicitly match the bus implementation, which is restricted to a single source (master) and a single destination (slave). This presents a problem as the number of voltage rails required by an electronic system increases, in that it becomes difficult to constrain specifically which voltage rails are supported over which interface, since multiple interfaces are required, and having dedicated interfaces for each rail is undesirable due to the higher implementation cost of supporting additional ports, pins and signals.
For example, by supporting multiple voltage rails over a single interface, the implementation is constrained to a single-master, single-slave configuration. However, there are several situations where a single-master approach is not suitable, such as when the voltage rails are distributed among several different physical entities, e.g. ICs or modules, and communication between the entities is limited and when the voltage rail is shared among multiple entities, all of which could benefit from having a connection to the power system management. Additionally, there are situations where a single-slave approach is not suitable, such as when the voltage rails are implemented over multiple entities, e.g. controller or integrated POLs (point-of-loads), which require their own dedicated slave interface.
A solution which improves the flexibility of multi-rail support for point-to-point power management interfaces is desirable.